1. Field of the Invention
The present invention relates to an ultrasound transducer array for forming an ultrasound transducer section having a curved shape provided on a distal end portion side of an ultrasound endoscope, a method of manufacturing the ultrasound transducer array, and an ultrasound endoscope.
2. Description of the Related Art
In recent years, an ultrasound diagnostic method for irradiating ultrasound on an inside of a body, imaging a state of the inside of the body from an echo signal of the ultrasound, and diagnosing the state of the inside of the body has been widely spread. Examples of medical apparatuses used in such an ultrasound diagnostic method include an ultrasound echo apparatus that can image a state of an inside of a body from a body surface and an ultrasound endoscope that includes an ultrasound transducer section, which transmits and receives ultrasound, at a distal end portion and can be inserted into a body and image a state in an inside of the body.
Among the medical apparatuses for ultrasound diagnosis, in particular, the ultrasound endoscope has been variously contrived to improve insertability into the body and reduce a diameter to ease pains of patients. Therefore, the ultrasound transducer section has been reduced in size and has been variously contrived to reduce the size.
In the ultrasound transducer section that is used in such an ultrasound endoscope and can realize a reduction in size, for example, a c-MUT (capacitive micromachined ultrasonic transducer: capacitive micromachined ultrasound probe) is sometimes used.
The c-MUT is formed by patterning a plurality of c-MUT cells on a substrate using a lithography technique. A flexible film is provided to cover the plurality of c-MUT cells on the substrate, whereby a c-MUT array, which is an ultrasound transducer array, is formed.
In ultrasound endoscopes of a radial scanning system and a convex scanning system, the ultrasound transducer section needs to be formed in a curved shape.
Therefore, in a publicly-known conventional method, a c-MUT array including transducer elements configured by a plurality of c-MUT cells is subjected to dicing using a dicing saw to form dividing grooves respectively in the c-MUT cells to form the transducer elements. Thereafter, the c-MUT array is bent to the dividing groove side to reduce width of the plurality of dividing grooves, whereby an ultrasound transducer section having a curved shape is formed.
Examples of such an ultrasound transducer section having the curved shape include an ultrasound transducer described in Japanese Patent Application Laid-Open Publication No. 2008-110060.
The ultrasound transducer described in Japanese Patent Application Laid-Open Publication No. 2008-110060 includes a flexible sheet, a rigid body portion made of a thin-film conductive material on a surface on one side of the flexible sheet, dividing portions, which are dividing grooves, for dividing the rigid body portion into a plurality of pieces to be apart from one another, and a transducer element including c-MUT cells including the rigid body portions divided by the dividing portions. After the dividing portions are respectively formed to reach the flexible sheet by dry etching from a surface side on which the c-MUT cells of the transducer element are arranged, the dividing portions are respectively extended to form, in a curved shape, the surface on which the c-MUT cells of the divided respective transducer elements are arranged.